Technologies

Data Logging and Telemetry Fundamentals

Manual or Automated? Depending on the use and importance of the information being collected, one of the initial questions to ask is: “How often do I need this information, and how important is this information to my operation?” If the information has value, you want to be sure that a system is in place so that it is recorded on a reliable device, and that the information is inspected regularly.

Automated data collection telemetry can be approached as either individual sites, networked sites, or a “network of networks”. The key to successful and sustainable monitoring programs is to select the right equipment to meet current needs, while having the potential for future adaptability and flexibility. Selecting the right telemetry depends on the type of information needed, placement of data collection, and availability of communication services, such as cellular availability or high speed internet. The diagram below highlights various options available through automated data collection.

Sensor Fundamentals

Sensors are available in many shapes, size, accuracies and price ranges from numerous manufacturers. There are generally many different technical and practical approaches that can be taken to gather information.

Below highlights the various technical ways that rainfall can be measured. Each approach has advantages and disadvantages, including factors such as accuracy, features, cost, compatibility and site suitability.

The tipping bucket rain gauge consists of a funnel that collects and channels the precipitation into a small seesaw-like container. After a known amount of precipitation falls (typically 0.1 or 0.2 mm), the lever tips, dumping the collected water and sending an electrical signal to an attached logging instrument.

Optical Rain Gauge

The optical rain gauge consists of a funnel that collects and channels the precipitation into a single point. When enough water is collected to make a single uniform drop of known volume, it drips from the bottom, falling into a laser beam path. The laser sensor is set at right angles to the water, and the dripping of the water droplet is detected. This break in the laser / optical sensor circuit allows an electrical signal to an attached logging instrument.

Weighing Gauge

A weighing precipitation gauge consists of a storage bin, which is weighed to record the mass. The advantages of this type of gauge is that it can measure other forms of precipitation not only liquid precipitation, including rain, hail and snow.

Impact Gauge

A piezoelectric sensor detects the impact from precipitation. The signal generated from the impact is converted to an equivalent volume of water. Advanced mathematical techniques including noise filtering are applied in order to perform the accurate conversion to rainfall volume.